Improve PowerShell EncodedCommand usage

[kke]

The powershell.Cmd now auto-detects if the script contains \n, \r, or " and uses -EncodedCommand (safe for cmd.exe), otherwise it uses -Command "..." so the script is visible in logs. Simple one-liners like $env:COMPUTERNAME, [DateTimeOffset]::UtcNow.ToUnixTimeSeconds(), registry reads, etc. are now human-readable.

Part of the rig v2 last-mile effort, breaking API is not a problem as rig v2 has not been released.

[Copilot]

Pull request overview

This PR updates the PowerShell command builder to prefer human-readable -Command "..." for simple one-liners while falling back to -EncodedCommand for scripts that are more likely to break when routed through cmd.exe, improving log readability as part of the rig v2 effort.

Changes:

• Update powershell.Cmd to choose between -Command and -EncodedCommand based on script contents, and document the behavior.
• Add unit tests covering selection logic and log readability expectations.
• Update a Windows FS test comment to reflect the new matching strategy (prefix-based, not always encoded).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
powershell/powershell.go	Implements conditional -Command vs -EncodedCommand selection and updates function docs.
powershell/powershell_test.go	Adds tests validating when Cmd uses -Command vs -E and that simple scripts remain visible.
remotefs/hostinfo_test.go	Updates comment explaining PowerShell command matching assumptions in tests.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

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[Copilot]

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Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

cmd/executor.go:205

• decodeUTF16LE / decodeEncoded behavior changed (now UTF-16LE decoding for PowerShell -EncodedCommand), but there’s no unit test coverage for this log-decoding path in cmd. Adding a small internal test (package cmd) that feeds a known powershell.exe ... -E <payload> string and asserts the decoded output would help prevent regressions (and would catch index/precedence issues here).

func decodeUTF16LE(encoded string) (string, error) {
	raw, err := base64.StdEncoding.DecodeString(encoded)
	if err != nil {
		return "", err
	}
	if len(raw)%2 != 0 {
		return "", fmt.Errorf("odd byte length in UTF-16LE payload")
	}
	words := make([]uint16, len(raw)/2)
	for i := range words {
		words[i] = uint16(raw[i*2]) | uint16(raw[i*2+1])<<8
	}
	return string(utf16.Decode(words)), nil
}

func decodeEncoded(cmd string) string {
	if !strings.Contains(cmd, "powershell") {
		return cmd
	}

	parts := strings.Split(cmd, " ")
	for i, p := range parts {
		if p == "-E" || p == "-EncodedCommand" && len(parts) > i+1 {
			if plain, err := decodeUTF16LE(parts[i+1]); err == nil {
				parts[i+1] = plain
			}
		}
	}
	return strings.Join(parts, " ")
}

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Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

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Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

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